I had to pull over on my way into work this morning to snap a picture of the steam rising up out of the big lake in front of the lift bridge.

As Jay Austin, Professor at UMD’s Large Lakes Observatory explains, “the steam is simply Lake Superior water evaporating, then condensing from gas to liquid droplets as it hits super-cold air. In general, Austin says, “evaporation is strongest when the air temperature is much lower than the water temperature.”

An ice-coated boulder is surrounded by steam rising from the surface of Lake Superior a few miles up the shore from downtown Duluth.

While temperatures have barely eked above zero for the past several days, it’s still been a relatively warm winter in Duluth. Austin says “the fact we’re not seeing much ice cover is a testament to the enormity of the lake – the lake needs to be sufficiently cooled down at the surface for ice to form.” So, Austin explains, the lake has been busy playing “catch up” the last few days.

Austin, of course, understands this from the perspective of a highly-regarded physicist and expert on large lakes. Still, he admits he’s even amazed to look at the huge stretches of open water when temperatures are so cold.

“Think of the temperature difference – +32F water, -10F air – that’s huge! And lots of heat is being lost to the atmosphere because of it.”